Some electrically operated devices, such as data storage devices, are housed in protective enclosures. Some enclosures, also referred to as housings, may be sealed. One reason that an enclosure may be sealed is to keep out contaminants, such as water vapor, smog, dust, and various other substances. Such contaminants, if allowed into the enclosure, may cause malfunctions of electronic, electromechanical, and mechanical components housed within the enclosure. Over time, such contaminants may cause corrosion, interfere with moving parts, degrade performance of lubricants, and otherwise generally degrade the performance of sensitive components. Accordingly, sealed enclosures may extend the service life and maintain the performance of the components that they house.
In general, a substantially sealed enclosure may inhibit the exchange of gasses into or out of the enclosure. Large differential pressures may deform the walls of some sealed enclosures. However, a small deformation in the enclosure wall of a sealed hard disk drive (HDD) enclosure, for example, could lead to catastrophic failure (e.g. head disk crash and permanent data loss). Enclosure wall deformation may occur, for example, due to internal heating of gasses within the enclosure that results from the operation of certain heat-dissipative components. In another example, enclosure wall deformation may result from altitude-related pressure changes experienced during shipment or transport by airplane. During ascent, external pressure decreases tend to expand the enclosure walls. Conversely, during descent, external pressure increases tend to crush the enclosure walls.
Various approaches may be used to address the differential pressure problem. One approach is to make the enclosure walls strong enough to withstand peak differential pressures. However, using stronger materials may involve increasing wall thickness or using stronger materials. Increasing wall thickness may add significantly to the weight of the enclosure, and may also make it more difficult to meet industry-standard, low-profile form factors. In addition, using a stronger material may significantly increase the cost of the enclosure.
An alternate approach that may be used to address the differential pressure problem is to incorporate a breather port. A breather port may be an aperture in the enclosure to allow the internal and external pressures to equalize. By allowing pressure to equalize, the enclosure may not need to be designed to withstand significant differential pressures. As such, thin, inexpensive, and lightweight materials, such as thin aluminum stock, may be used for some enclosures.
However, a breather port may also allow external ambient gasses, and any contaminants they carry, to be drawn into the sealed enclosure in an uncontrolled manner. In a data storage device, for example, such contamination may contribute to data errors in the read/write operations, corrode components, degrade lubricants, and otherwise generally reduce the service life of the device.